Hydraulic brake.



2 Sheets-Sheet Ililllllltllllllfla il! ||||||||l IIIII Patented Aug. 2|, |900.

Pill!!!IlItlillilllvlilllllllfllll F. L. CLARK. HYDRAULIC BRAKE.

(Applcatiun led June 7, 1899.)

(No Model WITNESSES:

- Patented Aug. 2|, |900. F. L. CLARK.

HYDRAULIC BRAKE.

(Application filed June 7, 1899.) v

' 2 Sheets-.Sheet 2.

No. 656,5I7.

(No Mndlel.)

:as co, Puoroumo., wAsHmarnN D c UNITED STATES 4PATENT Crrrcn'.

FRANCIS L. CLARK, OF PITTSBURG, PENN SYLYANIA, ASSIGNOR TO THE VESTINGIIOUSE AIR BRAKE COMPANY, OF SAME PLACE.

y, y 'HYDRAULIQ BRAKE- SPECIFICATION fomng part Of Letters Patent NO. 656,517, dated August 21, 1900. Application filed June 7,1899. Serial No. 719,667. .(No model.)

To all whom it' may con/cern:

Be it known that I, FRANCIS L. CLARK, of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a certain new and useful Improvement in Hydraulic Brakes, of which improvement the follow ing is a specification.

My present invention relates to and is an improvement in hydraulic bra-ke apparatus of the general character of that set forth in Letters Patent of the UnitedStates Nos. 574,663 and 574,665, granted and issued to me under date of January 5, 1897, and No. 615,141, to the Clark Brake Company, as my assignee, under date of November 29, 1898. .Said Letters Patent exemplify means for preliminarily taking up the slack of the connections and the clearances between the brake-shoes and the wheels and subsequently applying the brakes by the action of separate and independent brake-cylinder pistons; and the object ot' my present invention is to provide a more effective and desirable controlling-valve mechanism for application in a brake system in the operation of which the above-stated functions are performed. f

The improvement claimed is hereinafter fully set forth. f Y

In the accompanying drawings, Figure lis a vertical longitudinalcen tral section through a brake-cylinder and controlling-valve mechanism embodying my invention; andIfigs. 2, 3, and 4, similar sections, on an"`enlarged scale, through the controlling-valve mechanism detached, showing the movable members in dierent positions assumed by them in operation.

In the practice of my invention I provide two brake-cylinders 6 6 of larger and smaller diameters, respectively, which are connected in line axially through an interposed head 6b and are provided with pistons 56 51", acting through their piston-rodsupon "a system of brake-levers,,substantially as in the construction shown in Fig. 3 of Patent No. 615,141, aforesaid. The "brake-cylinders differ, however, from those shown in said figure in the particulars that a liexible diaphragm 51,working between the cylinder-head 6b and a perforated stop-plate 53, is employed in lieu of the piston 51 of said figure. The piston-rod the release of pressure within it.

sleeves work through stuffing-boxes in the cylinder-heads, and release-pipes, controlled by a cock, are provided for drawing oit1 liquid as desiredfrom the cylinder-spaces in which the pistons 56 and 511 and the diaphragm 51 operate. tion herein set forth accords substantially `with that set forth in Letters Patent of the `United States No. 641,625, granted and issued to me under date of January 16, 1900, and they are not in and of themselves claimed as of my present invention.

` As in Patent No."615,141 aforesaid, a rod 114, which abuts against the piston 51b of the smaller brake-cylinder 6a, is coupled by a pin 14 to one end of a brake-lever 17, the oppo= site end of which is connected bya brake-rod 25 to the brake-beam (not shown) of one pair of wheels of the car. A rod 16, which abuts `against* the piston 56 of the larger brake-cyliuder 6, is coupled by a pin 16 to one end of a brake`lever 17, the opposite end of which is connected by a brake-rod 25 to the brake* beam of another pair of wheels of the car. The brake-levers 17 17 are intermediately connectedy by a brake-rod 18.

The supply and discharge of liquid toand from the brake-cylinders 6 6 in the applica# tionand release, respectively, of the brakes are effected by a` valvular mechanism infclos'ed ina casing 4:0, which communicates by a pipe 5f, leading 'to a port in its peripheral wall, with a pipe which extends to a pump or other source of liquid under pressure and `which also serves for the discharge of liquid on the cessation of operation of the pump or A pipe 5h connects another port 49 in thefvalve-casing withthe larger brake-cylinder 6, between the headi6b thereof and the diaphragm 51. Direct communication between the pipe 5 and the pipe 5f is controlled by arelease checkvalve 52, which opens upwardly or toward the pipe 5f. A pipe 5g leads from another side port in the valve-casingliO to the smaller brakecylinder 6, The traverse ofj liquid from the pipe 5f to the pipes 5g and 5h is controlled, as presently to be described, by two lift or poppet valves li7 47, a piston 4:9, and a diaphragm 50, all of which are fitted to work in the valve-casing 40, and the release or return In these particulars the construe,

IOS

of liquid from the pipes 5g and 5h to the pipe 5f is controlled by said valves, piston, and

with the port 49b,which is open to the pipeV 5h. The valve 47a is secured upon a stem 48 and is adapted to seat around and close the `ripper end of the central bore 49a of the piston 49. The valve 47 is of greater diameter than the valve 47a, and the diaphragm 50 is of greater diameter than the piston 49. The valve 47 is normally held by a spring 51c off a seat formed around the upper end of a passage 47b in a wall or partition in the casing which separates the side ports therein to which the pipes 5f and 5g are respectively connected, and the valve 47 is connected to the stem 4S of the valve 47a, so as to be movable coincidently with the latter. A spring 51c in an extension 4()a of the valve-casing bears against the lower side of the diaphragm 50, and the tension of said spring may be varied as desired by an adjusting-screw 51a.

Fig. 1 shows the parts in running positionthat is to say, when the brakes are fully released and when liquid under pressure may be admitted to the brake-cylinders to effect an application of the brakes. The brake-cylinder spaces behind the pistons are supposed to be full of liquid, and excess slack has been taken up, forcing the piston 56 and diaphragm 51 apart and interposing liquid between them which liquid is subject to the pressure exerted by the spring 22 of the smaller brakecylinder piston 51h.

. In effecting an application of the brakes liquid under pressure enters the valve-casing 40 from the pipe 5f and passes through the passage 47h, controlled by the valve 47, into the pipe 5g, and thence to the smaller brakecylinder 6, forcing out the piston 51b thereof, and thereby taking up the slack of the connections and bringing the brake-shoes against the Wheels, as Well as moving the axle-boxes up to their bearings in the pedestals. The pressure exerted by the liquid on the piston 51b is transferred through the levers and connecting-rods to the brake-beams, and as the piston 56 and its push-rod 16 constitute the fulcrum or abutment at which the series of levers ends a force equal to that exerted by the liquid on the piston 51b will be transferred to the piston 56 and by said piston, through the interposed liquid, to the diaphragm 51 and to the liquid on the right or outer side thereof. This pressure per square inch will be as the relative areas of the pistons 51 and 56.

When the liquid-pressure in the valve-casing 40 on the top of the piston 49 (from the pipe 5f) plus the pressure on the top of the diaphragm 50 (from the larger brake-cylinder and pipe 5h) exceeds the pressure of the spring 51c on the diaphragm 50, the piston 49 is moved down, allowing the valve 47 to be closedv by the spring 4t n, and communication between the pipes 5f and 5g is thereby cutoff and the liquid in both the smallv and large cylinders is locked therein. At this time the liquid-pressure in the pipe 5f holds the checkvalve 52Yclosedagainst the pressure on the inner side of the diaphragm 51 of the larger cylinder 6, said diaphragm having been theretofore subjected to such pressure from the piston of the smaller cylinder through the lever-and-link connections between the pistons 51D and 56 and the body of liquid interposed between the piston 56 and the diaphragm 51. Liquid is therefore locked in both the cylinders 6 and 6a.

Upon the further increase of pressure in the casing 40 sufficient to move lthe piston 49 against the increasing resistance of the spring 51c with the decreased area of the piston 49, due to the seating of the valve 47, holding the valve 47 a further downward movement of the piston 49 is eifected, thereby moving it away from the valve 47a and admitting liquid under pressure from the pipe 5f to the top of the diaphragm 50, which being of still larger area than the piston 49 overcomes the still increasing resistance of the spring 51c and opens the portage under the valve 47 to its full extent, thereby admitting fluid under pressure from the pipe 5f through the pipe 5h to the larger cylinder. Liquid then passes from the pipe 5f through the passage 49, port 49h, and pipe 5h into the cylinder 6, moving the diaphragm 51 thereof outwardly' or to the left, said diaphragm, through the liquid interposed between it and the piston 56, also moving the piston 56 in the same direction. As soon as the liquidpressure passes into the larger cylinder the direction of pressure is reversed and the piston of the smaller cylinder becomes the fulcrum, the pressure per square inch in the smaller cylinder rising in proportion to the relative transverse areas of the cylindersand holding the valve 47 firmly to its seat. This movement of the diaphragm 51 and piston 56 applies the brakes with the desired degree of force, andthe pressure reacts through the brake-leversand connections, the pin 14a acting as a fulcrum, and proportionately raises the pressure in Ithe smaller cylinder 6a.

Upon the release of pressure in the pipe 5f for the purpose of releasing the brakes the pressure in the larger brake-cylinder 6 unseats the release check-valve 52, as shown in Fig. 4, and the pressure on the right-hand side of the diaphragm 51 thereby falls below that at which the movable members of the controlling-valve mechanism are held in the positions shown in Fig. 3, relieving the pressure on the top of the piston 49 and diaphragm 50, which thereupon move upwardly unt-il the valve 47a is seated by the contact of the piston 49 therewith, as shown in Fig. 4. The pressure in the larger brake-cylinder IOO IIO

6 and on the top of the piston 49 and diaphragm 50 decreases as the liquid is discharged from the space on the right-hand side of the diaphragm 5l by the combined action of the spring 59 and the pressure in the smaller brake-cylinder 6a acting through the levers on the piston 56 and the liquid interposed between said piston and the diaphragm 5l. Said diaphragm 5l is brought to the position shown in Fig. 1 and again becomes the fulcrum or abutment for the piston of the smaller cylinder, relieving the pressure in the smaller cylinder and on the top of the valve 47. The pressure on .the top of the valve 47 being less than thetension of the controlling-valve spring 5.1, said spring further raises the piston 49 of the controllingvalve mechanism and unseats the valve 47, and liquid from the smaller cylinder passes through the pipe 5g and passage 47b to the pipe 5f, leaving the parts in the positions shown in Fig. 1.

Liquid which may leak past the pistons 56 and 51b is discharged to the pipe 5f through the release-pipes 60b and 60, controlled by a release-cock 60a, when said cock is in the position shown in Fig. 1, and liquid may be discharged from the space between the piston 56 and diaphragm 51 as desired through the pipe 60a by turning the release-cock a quarter of a revolution from the position shown. The construction of my present invention accords substantially in these particulars with that of my Letters Patent No. 641,625, aforesaid.

The improved controlling-valve mechanism which is herein set forth presentsin practice the substantial advantage of enabling communication between the pipey 5f and the smaller cylinder to be positively and effectively closed before communication is opened from the pipe 5f to the larger cylinder, so .that liquid may be locked With certainty in the smaller cylinder to enable its piston to act as an abutment for that of the larger cylinder. The employment of the diaphragm 50 in combination with the two Vsuperposed lift-valves completely prevents leakage and loss of liquid, and the entire construction is more easily i constructed and maintained and more certain in its operation than those of the prior patents referred to.

I claim as my invention and desire to secure by Letters Patent- 1. In amechanism for applying hydraulic pressure, the combination, substantially as set forth, of two cylinders, of dierent areas of transverse sections, pistons fitted therein, two movable pressure members, connections coupling the pistons one to the other and to the pressure members, a pipe for the supply and release of liquid under pressure, a valvecasing communicating therewith, a piston f1tting therein and having an internal passage communicating with the larger cylinder, a diaphragm secured peripherallyin the casing and connected to said piston, a spring bearing on said diaphragm, a valve controlling communication between the liquid supply and release pipe and the smaller cylinder, a valve of smaller diameter connected' thereto and adapted to control the internal passage of the piston, and a release check-valve controlling communication between the larger cylinder and the liquid supply and release plpe.

2. In a brake apparatus, the combination, substantially as set forth, of a larger and a smaller brake-cylinder connected by an interposed cylinder-head, pistons fitted in said cylinder, connections coupling said pistons one to the other and to brake-operating levers, a flexible diaphragm and a perforated stop-plate, each fixed peripherally to the larger cylinder adjacent to the interposed cylinder-head, a liquid supply and release pipe, pipes leading therefrom to the smaller cylinder and to the space between the flexible diaphragm and the adjacent cylinderhead, a valvular mechanism, actuated by oppositely-exerted liquid and spring pressures, through which valvular mechanism and passages controlled thereby liquid under pressure is delivered to the smaller cylinder and to the space between the diaphragm of the larger cylinder and the adjacent cylinderhead, and a release check-valve controlling communication between said space and the liquid supply and release pipe.

FRANCIS L. CLARK.

Witnesses:

J. SNowDEN BELL, CLARENCE A. WILLIAMS. 

